One of the most important concerns in virtually all software/firmware and computer-based systems is security. Customers demand assurance that, while using a particular system, their information and transactions are safe, and that the wrong users are not given access or able to perform unauthorized actions. In order to satisfy diverse security needs, various security technologies, such as strong encryption and authentication methods, are continually developed. However, while manufacturers may promote the various security features implemented in a system, this may mean next to nothing to an average customer without technical knowledge of the features. Even systems engineers may have difficulty seeing the “big picture” when determining which security features to implement in a system. In the end, the question that must be answered is, “How secure is this system?”
Representing security in terms of a single number does not provide the granularity needed to secure the system. In contrast, a single number or measure may be used to accurately convey the throughput of a network card: a network card may support transfer speeds of, for example, 10, 100, or 1000 megabits per second. A single number or measure would be almost meaningless with regard to system security because there are many distinct facets of security that are likely to be relevant. In most cases, a single number could not capture the entire picture as it would be unable to convey the particular strengths and, more importantly, weaknesses of a system's security.
As an example of the numerous facets encompassed by the term “security,” international standard ITU-T X.805, incorporated herein by reference, defines eight “security dimensions,” each describing a separate security concern. Privacy and data integrity are two examples of these security dimensions. ITU-T X.805 also explains that each security dimension is applicable on each of three security planes as well as each of three security layers. Each security dimension provides the necessary granularity to measure security in a repeatable way over and above the traditional industry known parameters CIA (confidentiality, integrity, availability) or AIC (availability, integrity or confidentiality). Security layers describe the area-of-focus and represent the assets within the equipment or systems hierarchy and include the infrastructure, services, and applications layers. Security planes describe the types of activities occurring in a system and include end-user, control/signaling, and management planes. Thus, according to ITU-T X.805, there are 72 dimension-layer-plane combinations which are relevant to system security and should be taken into account for a complete security assessment.
In view of the foregoing, it would be desirable to reliably estimate and convey the security level of an actual or planned system. In particular, it would be desirable to present an estimation of system security in an intuitive and repeatable manner while also conveying the particular security strengths and weaknesses of the system. It would also be desirable to aid system designers in determining which security features should be implemented in a particular system and the effects of such security features on the overall security of the system.